Method for fabricating a preform for plastic optical fiber

Abstract

A method for fabricating a preform for a plastic optical fiber, comprising: (1) preparing a pair of monomer solutions having different refractive indices; (2) polymerizing a monomer solution having a lower refractive index than the other to form a prepolymer; (3) homogeneously mixing the prepolymer with the other monomer solution to obtain a mixture; and (4) feeding the mixture into a reactor and polymerizing the mixture while the reactor is being rotated. According to the method, a preform for a plastic optical fiber can be fabricated from monomers selected irrespective of their density.

What is claimed is:  
     
         1 . A method for fabricating a preform for a plastic optical fiber, comprising: 
 (A) preparing a pair of monomer solutions having different refractive indices;    (B) polymerizing a monomer solution having a lower refractive index than the other to form a prepolymer;    (C) homogeneously mixing the prepolymer with the other monomer solution to obtain a mixture; and    (D) feeding the mixture into a reactor and polymerizing the mixture with the reactor rotated.    
     
     
         2 . The method for fabricating a preform for a plastic optical fiber as claimed in  claim 1 , wherein after step (4), the following step (5) is repeated one or more times: 
 (E) adding a monomer solution, a prepolymer or a mixture of a monomer solution and a prepolymer, having a high refractive index to a cavity formed in the reactor, and continuing polymerization.    
     
     
         3 . The method for fabricating a preform for a plastic optical fiber as claimed in  claim 1 , wherein in step (B), the monomer solution is polymerized through thermal polymerization and/or photopolymerization to prepare a prepolymer.  
     
     
         4 . The method for fabricating a preform for a plastic optical fiber as claimed in  claim 1 , wherein in step (D), the mixture in the reactor is polymerized through thermal polymerization and/or photopolymerization.  
     
     
         5 . The method for fabricating a preform for a plastic optical fiber as claimed in  claim 1 , wherein the reactor is a cylindrical reactor with a circular cross-section.  
     
     
         6 . The method for fabricating a preform for a plastic optical fiber as claimed in  claim 1 , wherein the reactor is under constant or variable rotation.  
     
     
         7 . The method for fabricating a preform for a plastic optical fiber as claimed in  claim 6 , wherein the variable rotation of the reactor is carried out by a repeated high-speed and low-speed rotation or stopping, or a rotational velocity function having varying cycles, phases and amplitudes such as a trigonometric function or a specific function.  
     
     
         8 . The method for fabricating a preform for a plastic optical fiber as claimed in  claim 1 , wherein the monomer solution comprises at least one monomer, a polymerization initiator and a chain transfer agent.  
     
     
         9 . The method for fabricating a perform for a plastic optical fiber as claimed in  claim 8 , wherein the monomer is selected from the group consisting of methylmethacrylate, benzylmethacrylate, phenylmethacrylate, 1-methylcyclohexylmethacrylate, cyclohexylmethacrylate, chlorobenzylmethacrylate, 1-phenylethylmethacrylate, 1,2-diphenylethylmethacrylate, diphenylmethylmethacrylate, furfuryl methacrylate, 1-phenylcyclohexylmethacrylate, pentachlorophenylmethacrylate, pentabromophenylmethacrylate, styrene, TFEMA (2,2,2-trifluoroethylmethacrylate), TFPMA (2,2,3,3-tetrafluoropropylmethacrylate), PFPMA (2,2,3,3,3-pentafluoropropylmethacrylate), HFIPMA (1,1,1,3,3,3-hexafluoroisopropylmethacrylate), HFBM (2,2,3,4,4,4-hexafluorobutylmethacrylate), HFBMA (2,2,3,3,4,4,4-heptafluorobutylmethacrylate) and PFOM (1H,1H-perfluoro-n-octylmethacrylate).  
     
     
         10 . The method for fabricating a perform for a plastic optical fiber as claimed in  claim 8 , wherein the polymerization initiator is a thermal polymerization initiator selected from the group consisting of 2,2′-azobis(isobutyronitrile), 1,1′-azobis(cyclohexanecarbonitrile), 2,2′-azobis(2,4-dimethylvaleronitrile), 2,2′-azobis(methylbutyronitrile), di-tert-butyl peroxide, lauroyl peroxide, benzoyl peroxide, tert-butyl peroxide, azo-tert-butane, azo-bis-isopropyl, azo-normal-butane and di-tert-butyl peroxide.  
     
     
         11 . The method for fabricating a perform for a plastic optical fiber as claimed in  claim 8 , wherein the polymerization initiator is a photopolymerization initiator selected from the group consisting of 4-(para-tolylthio)benzophenone, 4,4′-bis(dimethylamino)benzophenone, 2-methyl-4′-(methylthio)-2-morpholino-propiophenone, 1-hydroxy-cyclohexyl-phenyl-ketone, 2-hydroxy-2-methyl-1-phenyl-propan-1-one, benzophenone, 1-[4-(2-hydroxyethoxy)-phenyl]-2-hydroxy-2-methyl-1-propan-1-one, 2-benzyl-2-methylamino-1-(4-morpholinophenyl)-butanone-1, 2,2-dimethoxy-1,2-diphenylmethan-1-one, bis(2,4,6-trimethylbenzoyl)-phenylphospinoxide, 2-methyl-1[4-(methylthio)phenyl]-2-morpholinopropan-1-one and bis(.etha.5-2,4-cyclopentadien-1-yl)-bis(2,6-difluoro-3-(1H-pyrro-1-yl)-phenyl) titanium.  
     
     
         12 . The method for fabricating a perform for a plastic optical fiber as claimed in  claim 8 , wherein the chain transfer agent is selected from the group consisting of normal-butyl-mercaptan, lauryl mercaptan, octyl mercaptan, dodecyl mercaptan, and 1-butanethiol.  
     
     
         13 . The method for fabricating a preform for a plastic optical fiber as claimed in  claim 1 , wherein the prepolymer has a viscosity of 50˜500,000 cps (25° C.).